Circuit breaker device including simplified housing assembly and external contacts



Aprzl 8, 1969 H. R. SHAFFER ET AL 3,437,970

CIRCUIT BREAKER DEVICE INCLUDING SIMPLIFIED HOUSING ASSEMBLY AND EXTERNAL CONTACTS Original Filed Sept. 7, 1966 Sheet of 3 By 64/414 5. GAYCTAO April 8, 1969 H. R. SHAFFER ET AL 3,437,970 CIRCUIT BREAKER DEVICE INCLUDING SIMPLIFIED HOUSING ASSEMBLY AND EXTERNAL CONTACTS Original Filed Sept. 7, 1966 Sheet 2 of 3 dyreazf/m ISMFA @zex fame April 8, 1969 H SHAFFER ET AL 3,437,970

CIRCUIT BREAKER DEVICE INCLUDING SIMPLIFIED HOUSING ASSEMBLY AND EXTERNAL CONTACTS Original Filed Sept. 7, 1966 Sheet 3 of s 0 712045710 5,554 ee fJrwv United States Patent U.S. Cl. 33791 3 Claims ABSTRACT OF THE DISCLOSURE A compact and relatively inexpensively constructed ClICllll. breaker having complementary housing halves provided with extensions forming plug-in type cylindrical contacts.

Our invention relates to circuit breaker devices of simpl fied construction and operation, and more particularly to such circuit breaker devices which have a housing sufficiently compact and of a suitable configuration to permit their installation in those applications previously utilizing replaceable type cartridge fuses, and is a division of U.S. patent application Ser. No. 577,772, filed Sept. 7, 1966, now U.S. Patent No. 3,379,843.

In the protection of electrical circuits from a short circuit or other overload conditions, it is the general practice to include a circuit protective device between the power source and the load. The circuit protective device is designed to respond to circuit conditions above a predetermined value, for automatically interrupting the current flow to the load. In many applications such protection is afforded by a fuse which will rupture when subjected to a current above its rated value. Once the fuse has operated to protect the circuit, it is destroyed and it is necessary to remove the fuse and replace it with another one. A much more desirable protective device is an automatic circuit breaker which will trip open responsive to predetermined overload conditions and interrupt the current flow. The circuit breaker device is not destroyed by its protective operation, as in the case of the fuse, but may then be reset (typically by a conveniently accessible manual operating handle) to provide subsequent circuit protection.

In the past, circuit breaker devices have generally been of such "a size and of such costs as to generally restrict their utilization in numerous applications where only a limited expenditure is commercially practical; e.g., the protection of automotive accessories. Our invention, however, provides a circuit breaker device of such simplicity of operation, compactness of size and ease of fabrication that it may be economically utilized in those environments which previously have been generally restricted to the utilization of replaceable fuses.

It is therefore seen that a basic concept of our invention resides in the provision of an automatic circuit breaker device of increased simplicity of operation, compactness of size and of reduced cost.

It is therefore a primary object of our invention to provide a circuit breaker device of a type and size and having a terminal configuration which may be readily incorporated in those environments previously utilizing replaceable type fuses.

A further object of our invention is to provide such a circuit breaker device which may be readily substituted within mounting base assemblies presently designed for the reception of replaceable type cartridge fuses.

The circuit breaker device utilizing our invention is contained within a compact housing having a generally rectangular internal volume portion, including opposed sidewalls, a top wall and a bottom wall. A pair of stationary contacts are positioned along spaced locations of the bottom wall. A combined bridging contact and actuator is provided by an elongated bimetallic element, which is operatively connected to a plunger translatable along a path towards and away from the bottom wall. A portion of the plunger extends outward of the top wall to provide a manual operating handle. A flat spring member, slightly longer than the distance between the'sidewalls, has its opposed ends mounted in restraining recesses of the sidewalls in a manner arcing the spring about a center line passing through the sidewall recesses and restraining movement of the spring along its longitudinal length. The central portion of the spring is operatively connected to the plunger and the central portion of the bimetallic element. Overload responsive actuation of the circuit break er is provided by deflection of the bimetallic element, responsive to predetermined current flow therethrough, such that the arc of the spring will be urged towards its opposed overcenter condition. The movement across the center line is a snap action, to provide rapid separation of the contacts, thereby interrupting the current flow. Hence, there will be first and second operative positions of the spring, with the center of the arc in opposed overcenter relationship with respect to its restrained end locations. The spring will act in a manner analogous to an overcenter toggle, to provide snap action of the plunger between a first operative condition where the bimetallic element provides bridging contact between the stationary contact pair, and a second operative position where the circuit breaker has interrupted the flow of current between the stationary contact pair.

In accordance with a further feature of one form of our invention, the external contacts of the circuit breaker are in the form of circular members, analogous to the ferrule end tips of a cartridge type fuse. Thus, the circuit breaker device may be inserted within spring clips of the type provided on mounting blocks for receiving cartridge type fuse members. To further simplify the assembly of our circuit breaker and hence reduce its costs, the housing may be formed of first and second complementary sections held together by the ferrule type contacts, thereby eliminating the utilization of rivets or similar type securing means, previously required in circuit breaker devices. Advantageously, the ferrule type contacts may also have the circuit breaker stationary contacts integrally formed therewith, to further minimize the required number of arts. p In accordance with another aspect of the form of our invention using ferrule type contacts, it is desirable that once the circuit breaker device is inserted within the contact clips of the mounting, it be prevented from pivoting about the axis of the contact clips. This may be provided by a downward extension of the circuit breaker housing to provide interference for the tendency of the circuit breaker device to pivot about the terminal contact clips.

It is therefore seen that another object of our invention is to provide a circuit breaker device, which includes ferrule type contacts for convenient plug-in mounting to fuse-type spring contact clips, and further includes means to prevent the pivoting of the circuit breaker about the axis of the spring clips.

These as well as other objects of our invention will become readily apparent upon a consideration of the following description and drawings in which:

FIG. 1 is an exploded perspective view of a circuit breaker device constructed in accordance with one form of our invention, and shown in conjunction with the spring contact clips and mounting base, which may receive same.

FIGS. 2, 3 and 4 are side elevation, plan and end views respectively of the circuit breaker device of FIG. 1, shown mounted in its operative condition.

FIG. 5 is a cross-sectional view along the line 5--5 of FIG. 4, looking in the direction of the arrows, with the mounting block deleted, and showing the circuit breaker in its OFF condition.

FIG. 6 is a cross-sectional view corresponding to FIG. 5, but showing the circuit breaker in the ON condition.

FIG. 7 shows the circuit breaker device of FIGS. 5 and 6, corresponding to an overload condition, in which the bimetallic actuator has deflected and the circuit breaker is about to trip.

FIGS. 8, 9 and 10 are cross-sectional views, corresponding to FIGS. 5, 6 and 7 respectively, but illustrating a modified form of our invention.

FIGS. 11 and 12 are side elevational and end views respectively of a further form of our invention which includes combined arc chutes and auxiliary housing retainers.

FIG. 12 shows a typical inverse-time characteristic, which has been demonstrated by circuit breakers of the instant invention.

Referring initially to FIGS. 1-7, circuit breaker device 10 is enclosed within a housing including complementary housing sections 12 and 14. The housing includes an internal volume, having first and second sidewalls 16, 18, respectively, a top wall and a bottom Wall 22. First and second stationary contact means 24, 26 are positioned at space locations along the bottom wall 22.

Electrically connected to the stationary contact means are external contact means 28, 30, which, in the form shown in FIGS. 1-5, and according to our invention are of a generally circular configuration, of a size analogous to the ferrule ends of conventionally available cartridge-type fuse devices. External contact members 28, 30 tightly engage extensions 29, 31 of the housing, and in accordance with a particularly advantageous aspect of this form of our invention, may serve as the sole or principal retaining means for maintaining complementary housing sections 12, 14 in their abutting relationship.

The circuit breaker device 10 may be readily plug-in inserted within conventional type spring contact members 32, 34 mounted to base 36 and having screw-type contacts 38, 40 and receiving the leads (not shown) to the external circuit being protected by the circuit breaker 10.

Circuit breaker stationary contact pairs 24, 26 are of the bridging variety; that is, when an electrically conductive path is provided therebetween, a circuit will be provided through the circuit breaker device 10 intermediate external contact means 28-30. This bridging type contact is provided by the combined contact member and actuator 50, which is a bimetallic element. Bimetallic element is operatively connected to a first portion 52 of a plunger 60, such that as the first portion moves towards the bottom wall 22, contact engagement will be made by the ends 54, 56 of the bimetallic element 50, with stationary contacts 24, 26, respectively. End section 62 of the plunger rides within guide slot to provide vertically reciprocable movement.

A planar spring member 72 is mounted at its opposed ends 74, 76 within notched recesses 75, 77 of the housing sidewalls 16, 18, respectively, for receiving said spring member '72 and restraining it against longitudinal movement. The central portion of the spring member is operatively connected to a second portion 53 of the plunger 60. Spring member 72 is of a length greater than the distance between sidewall notches 75, 77, and hence will define an are about center line 100. Spring 72 may be actuated between opposed overcenter positions as shown in FIGS. 5 and 6 respectively. In FIG. 6, the plunger rod 60 has been moved downward, such that the bimetallic element 50 provides bridging contact between stationary contact means 24, 26, and current flow is provided therethrough. Responsive to predetermined overload conditions, in accordance with the thermal calibration of bimetallic element 72, the bimetallic element will begin to distortively deflect, as shown in FIG. 7, such that the plunger rod 60 is gradually urged upward. When the point is reached that the spring moves past its overcenter position, there will be a rapid snap action, in the manner of an overcenter toggle structure, such that the contacts are rapidly disengaged to the condition of FIG. 5. The breaker will then remain in the disengaged position until manually reset by the pressing downward of plunger 60. Where desired, spring member 72 may be constructed of a bimetallic element to provide suitable compensation for ambient conditions.

In accordance with another aspect of the form of our invention shown in FIGS. 17, a downward housing extension 75 is provided to abuttingly engage the top surface of the terminal clip mounting block 36 and thereby prevent pivoting of the circuit breaker 10 about the axis of terminal clips 32, 34.

Reference is now made to FIGS. 8, 9 and 10, which show a modified form of our invention, in the operating positions corresponding to FIGS. 5, 6 and 7, respectively.

The form of the circuit breaker shown in FIGS. 8, 9 and 10 is basically similar to that previously discussed, with the exception that the plunge-in type ferrule contacts have been replaced with contact members 28', 30 respectively, including screw-type members 28" and 30" for receiving the connections to the external circuit being protected. The other elements of the circuit breaker device 10, which correspond in function to those shown in the previously discussed embodiments of FIGS. 1-7, are indicated by the same numerals but with prime designation, to readily permit their comparison.

FIGURES l1 and 12 show another modification of our invention, of particular utility for interrupting higher current magnitudes. U-shaped arc chute members are provided, having openings 117 to expel the gases generated during circuit interruption. Advantageously, arc chute members 115 are frictionally restrained by the walls of complementary cutouts of the housing sections 12", 14 to serve as a further means for maintaining the housing sections together.

FIGURE 13 shows a plot 120 of typical inverse-time characteristics which have been obtained with a circuit breaker according to our invention, with both the time 122 and current 124 parameters being indicated on a logarithmic scale.

It is therefore seen that our invention provides an extremely simple circuit breaker device of small size, providing a double break relationship between the stationary movable contacts, with snap action being achieved by a single flat-type spring member. Further, the circuit breaker and its external contacts may be made of a suitable size and configuration so as to be readily utilized in those environments previously restricted because of cost or size limitations to the use of replaceable type fuses.

Although there have been described preferred embodiments of this novel invention, many variations and modifications will now be apparent to those skilled in the art. Therefore, this invention is to be limited not by the specific disclosure herein, but only by the appending claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows.

We claim:

1. In a circuit breaker including:

a housing having an internal volume bounded by top,

bottom and side walls, with said internal volume enclosing stationary contact means and cooperating movable contact means;

an operating means connected to said movable contact means for moving said movable contact means into and out of engagement with said stationary contact means; I

said operating means including a manual operator passing through said top wall external of said housing for manually moving said contacts into and out of engagement;

said operating means further including an automatic trip means for automatically moving said contacts out of engagement responsive to a predetermined overload condition, and maintaining said contacts out of engagement until manually reset by said manual operator;

first and second external contact means along said first and second sidewalls, and adjacent said bottom wall, for electrically connecting said circuit breaker to an electrical circuit;

said external contact means being in coaxial alignment and having a substantially circular periphery adapted to be plug-in inserted and frictionally retained within cooperating circular mounting clips, whereby said circuit breaker may be plug-in mounted within a pair of cooperating mounting clips;

said cylindrical external contact means including an integrally formed portion extending within said in ternal volume and providing said stationary contac\ means;

said housing formed of first and second complementary sections in abutting relationship along a joining plane passing through all of said top, bottom and side walls, such that said internal volume is completely exposed along said joining plane;

each of said housing sections including first and second semicylindrical extensions with their mating circular regions lying within joining planes;

the extensions of said first and second housing sections in mating relationship to define first and second cyllindrical sections for receiving said first and second external contact means;

first and second cylindrical external contact means tightly engaging said extensions to provide a means for retaining said housing sections in abutting relationship.

2. In a circuit breaker as set forth in claim 1:

said cylindrical external contact means providing the sole assembly means for securably maintaining said complementary housing sections together.

3. In a circuit breaker as set forth in claim 1:

said housing sections including recesses for receiving and locating said cooperating contact means and operating means;

said recesses being completely accessible along said joining plane.

References Cited UNITED STATES PATENTS 2,458,804 1/1949 Sundt.

BERNARD A. GILHEANY, Primary Examiner. R. L. COHRS, Assistant Examiner.

US. Cl. X.R. 

